CONNECT SOLAR PANELS IN PARALLEL OR IN SERIES: When the voltage of your solar panel doesnt satisfy your storage battery, you can or more same solar panels together in series. Such as, two 9V solar panel connect together in series, so its voltage is 18V. When the voltage of solar panel satisfies your storage battery. In order to the rate of charge, you can or more same solar panel together parallel connection. DIY YOUR OWN SMART MODEL: powered models, solar toys, solar lights, solar displays, charging small DC batteries. It can be used for teaching purpose. Many of our customers e from school, colleague, etc. SOLID & WORK LONG HOURS: High conversion rate, high efficiency output, excellent weak light effect, as long as there is sunshine, it can work all the time. The shell is made of tempered glass and plastic yellow frame, which protect solar panels, and extend the life of solar panels. EDUCATION: Solar panels are devices that absorb sunlight and convert solar radiation directly or indirectly into electricity through photoelectric or photochemical effects, it's perfect devices for science project. ENVIRONMENTAL PROTECTION: Use solar panels to cut your carbon footprint, because it is green and renewable . Unlike conventional generators, solar power does not release any harmful carbon dioxide.